Atrio-ventricular conduction defects and arrhythmias by selective perfusion of the A-V conduction system in the canine heart

Ligation and cannulation of the anterior septal artery in 43 canine hearts caused changes in ST-T segment of the electrocardiogram in all animals. Perfusions of 0.9% NaCl, one to ten micrograms of acetylcholine, isoproterenol, epinephrine and norepinephrine, into the anterior septal artery caused variations in the ECG ranging from exaggerated ST-T changes to PR prolongation, ectopic atrial, nodal and ventricular beats, A-V blocks and dissociations, atrial fibrillation and ventricular fibrillation. The response seemed to be somewhat specific for cholinergic versus adrenergic agents showing more conduction defects by the former against greater changes in automaticity by the latter agents.